The objectives of this work are to characterize further mechanisms by which enzymes catalyze chemical reactions and to develop methods for obtaining information relating structures of proteins to their function. Information obtained from these studies should contribute to the development of improved methods for treating and characterizing metabolic diseases. We propose to study: 1. Kinetics of binding of chromogenic inhibitors to papain, in order to characterize conformational changes occurring when papain binds ligands. 2. Kinetics of displacement of chromogenic ligands from papain by substrates, in order to characterize individual steps in papain's catalytic cycle. 3. Presteady-state kinetics associated with the D-serine dehydratase-catalyzed reaction. 4. Difference between papain and non-activatable papain. 5. Imidazole-catalyzed lactonization of 2-hydroxymethylbenzamides as a model for the acylation step in the catalytic cycle of serine proteinases, in order to evaluate the effect of the orientation of the neighboring hydroxyl group on the efficiency of this reaction.